Preliminary data showed that preference for and consumption of alcohol (EtOH) by osteocalcin (OC) null mutant mice (KO) differs significantly from wildtype C57BL/6 (WT) mice. Their behavior both in terms of basic behaviors and in response to EtOH administration also differed. Circulating osteocalcin (pOC), a protein of bone origin which generally reflects osteoblastic activity, may be decreased or increased following EtOH consumption. Variation in EtOH intake depends on dose, age; gender, and duration of alcohol consumption. Furthermore, pOC is strongly affected by stressful stimuli, again varying with the type and duration of the stressor and the elapsed time following stress exposure, pOC is rapidly increased within 3 to 5 minutes of exposure to acute severe stressors and returns toward basal levels after 1 to 2 hours. Milder, anxiety producing stressors slowly decrease pOC over 1 to 2 hours. It is also accepted that stressful experiences tend to increase alcohol consumption. There have been reports of immunolocalization of OC protein in sympathetic ganglia of rats, and of expression of OC mRNA in brain of rats and mice. Experimental approach: Research proposed here will (1) evaluate alcohol consumption and preference in KO and WT mice, (2) determine effect of acute supplementation of OC on EtOH drinking in KO mice, (3) evaluate EtOH drinking. and hormonal responses to restraint stress, and (4) probe for presence of OC by immunolocalization in extraskeletal tissues, including sympathetic ganglia, spinal cord, and brain. Significance: To date: pOC has been used primarily as a biomarker of bone formation, yet it is consistently altered by EtOH ingestion and by various psychological stressors in ways that cannot be attributed to osteoblast activity. The literature on the association of EtOH ingestion and stress has been somewhat controversial. The proposed experiments are expected to provide at least one potential answer to this controversial field. The hormonal changes that affect ingestion of EtOH in response to a severe stressor may differ in KO mice. Thus we expect to provide initial evidence for a novel mechanism for stress associated changes in EtOH ingestion. Positive identification by immunocytochemistry of OC interaction with various neural locations will provide essential information regarding its potential site of action in regulating alcohol ingestion. Furthermore, the proposed experiments will demonstrate that pOC is not a passive component of plasma, but rather part of a feedback loop emanating from bone to regulate neural input involving EtOH consumption and response to stressful conditions.